1. Field of the Invention
The present invention relates generally to apparatus for supporting structure between bolted flanges, and more particularly, but not by way of limitation, to structure supporting apparatus which, in a particular nominal size, can be interchangeably sealingly clamped and centered between bolted flanges of varying pressure rating and design standard.
2. Description of the Prior Art
A great variety of apparatus adapted to be clamped between bolted flanges has been developed and used heretofore. For example, a variety of valves such as check valves, ball valves, butterfly valves and other valves have been developed which can be clamped between bolted flanges. In addition, a variety of rupture disk assemblies which are adapted for clamping between pipe flanges have been developed and used heretofore. Such valves and rupture disk assemblies are generally of a size and shape such that they fit inside the bolt circle of conventional pipe flanges and are centered between the flanges by the bolts. For example, U.S. Pat. No. 4,073,402 issued to Wood on Feb. 14, 1978 is directed to a preassembled pressure relief apparatus. The apparatus is comprised of a rupture disk supported between a pair of complementary support members, and the support members are of a size and shape such that they can be clamped between conventional pipe flanges.
U.S. Pat. No. 3,526,336 issued to Wood on Sept. 1, 1970 is directed to a reverse rupture disk supported between inlet and outlet support members. The support members are in turn adapted to be clamped between pipe flanges.
U.S. Pat. No. 3,815,779 issued to Ludwig et al. on June 11, 1974 is directed to a safety pressure relief device comprised of a rupture disk supported between a pair of annular support members adapted to be clamped between conventional pipe flanges. One of the support members includes an annular spacing member attached to the outside periphery thereof so that when the safety pressure relief device is clamped between the pipe flanges, the device is automatically centered therein.
Some of the valves, rupture disk assemblies and other similar devices adapted for clamping between conventional pipe flanges are of a design such that in a particular nominal size they can be interchangeably clamped between bolted flanges of the same nominal size of varying pressure rating. For example, the preassembled pressure relief apparatus described in U.S. Pat. No. 4,073,402 can be clamped between flanges of various pressure ratings, e.g., a preassembled pressure relief apparatus of a 6-inch nominal size can be clamped between 6-inch, 150 pound per square inch ASA raised face flanges and 6-inch, 300 pound per square inch ASA raised face flanges.
As is well understood by those skilled in the art, in the U.S. conventional pipe flanges are constructed in accordance with standards provided by the American National Standards Institute (ANSI). In a particular nominal size, the bolt circles and numbers of bolts used in the flanges change with changes in pressure rating. For example, a 2-inch, 150 pound per square inch flange has a bolt circle of 4.75 inches in diameter and 4 bolt holes while a 2-inch, 300 pound per square inch flange has a bolt circle of 5 inches in diameter with 8 bolt holes. In other countries, different standards are used, the most common of which are the German Industrial Norm (DIN) and the Japanese Industrial Standard (JIS). These design standards are different from the American standards and from each other, i.e., each standard utilizes different diameter bolt circles and numbers of bolts, and the bolt circles and numbers of bolt holes vary with different pressure ratings and nominal size. Thus, heretofore, structure supporting apparatus adapted to be clamped between conventional bolted flanges and centered therein by contact with the bolts can be interchangeably clamped between only a limited number of bolted flanges of varying pressure rating and/or design standard. That is, a structure supporting apparatus adapted to be clamped between a particular nominal size of ANSI flanges and centered therein by contact with the bolts cannot be interchangeably clamped between and centered in the same nominal size of flanges built in accordance with the DIN or JIS standards.
By the present invention, improved apparatus for supporting structure between bolted flanges is provided which in a particular nominal size can be interchangeably sealingly clamped and centered between bolted flanges of varying pressure rating and design standard.